Added SHT30 sensor node example app

examples/sht30_sensor_node.py

@@ -0,0 +1,25 @@
+
+__version__ = 21
+__app__ = 'sensor_node'
+
+
+DEPENDENCIES = [
+    ('lib/sht30.py', 'https://raw.githubusercontent.com/rsc1975/micropython-sht30/3b2ec7c46c9d63e37432009002ec1149da341ac7/sht30.py')
+]
+
+
+async def run(mqtt, name):
+
+    interval_sub = mqtt.subscribe('home/config/sensor_node/measurement_interval', cls=int)
+    location_sub = mqtt.subscribe('config/location', local=True)
+    from sht30 import SHT30
+    sensor = SHT30()
+    temperature, humidity = sensor.measure()
+    location = await location_sub.wait_for_value()
+    sensor_topic = 'home/sensors/{}/{}'
+    mqtt.publish(sensor_topic.format(location, 'temperature'),
+                 b'{:.2f}'.format(temperature), qos=1, retain=True)
+    mqtt.publish(sensor_topic.format(location, 'humidity'),
+                 b'{}'.format(humidity), qos=1, retain=True)
+
+    return await interval_sub.wait_for_value()